Expansible mandrel



Jan. 20, 1959 A. P; JouRDAlN 2,869,329

EXPANSIBLE MANDREL Filed Jan. 12. 1954 2 sheets-sheet 1 Jan 20 1959 A. P.'JOURDA1N EXPANSIBLE MANDREL Filed Jan. 12. 1954 2 Sheets-Sheet 2 III United States EXPANSIBLE MANDREL Andr Paul Jourdain, Embourg-lez-Liege, Belgium, as-

signor to Compagnie Internationale des Pieux Armes Frankignoul, Societe Anonyme, Liege, Belgium The invention relates to expansible mandrels such as is used for sinking tubes into the ground with a view towards forming a foundation pile by filling the tubes with concrete.

The invention is concerned more particularly with a mandrel including a plurality of radially movable longitudinal sectors so that the mandrel is capable of being introduced into and removed from the tube when the mandrel is contracted and of being pressed tightly against the tube upon expansion of the mandrel, so as to take the tube with it into the ground under the action of hammer blows or similar driving force on the top of the sectors, the said expansion being performed by pneumatic control.

The invention has especially for its object the providing of a mandrel of the type aforesaid which, while being of simple and lightweight construction, is of great strength and, more particularly, makes it possible to apply great striking forces onto the top of the mandrel without the latter being likely to undergo detrimental distortion.

With this end in view, the invention provides a mandrel including independent longitudinal sectors, the upper end of which is adapted to be subjected to the driving force applied by a driving means, a central member the upper end ofwhich is adapted to be subjected to the driving force from the said driving means at the same time as the said sectors, an enlarged base integral with the lower endY of said central member, an operative connection effective in a longitudinal direction, while exhibiting radial play, between the sectors and the said base, elastical means arranged between the sectors and the central member and tending to move the sectors towards the central member in order to contract the mandrel, and fluid pressure means arranged between each of the sectors and the central member to cause the mandrel to expand against the action of the elastical means when the Huid pressure is applied in the pressure means.

Each pressure means cooperating with one sector may comprise a rubber or like pipe having its lower end sealed, while its upper end is in communication with a source of fluid, the pipe being arranged in a longitudinal cavity, the inner wall of which is integral with the central member, while the opposite wall is integral with the sector.

Following a further provision of the invention, the resilient return means for each individual sector may be formed by an elastically co-mpressible pipe arranged in a cavity the outer wall of which is integral with the central member, while its inner wall is integral with the sector.

Further features and'advantages of the invention will appear from the disclosure of one example of carrying out the invention, as willbe given hereinafter with reference to the accompanying drawings, in which:

Figure l is partly a vertical sectional view and partly an outside view of a mandrel according to the invention in the expanded position, having arranged on the top of it a percussion head;

atent Patented Jan. 20, 1959 Fig. 2 s a sectional view, on an enlarged scale of a detail of the mandrel;

Fig. 3 is a plan view of Fig. 2; l

Fig. 4 is a horizontal sectional view on line IV-IV of Fig. 1, but on an enlarged scale, and

Fig. 5 is a view similar to Fig. 4, with the mandrel in the contracted position. f

The example illustrated is concerned with a mandrel for sinking a cylindrical tube having a corrugated wall, though it will be obvious that the mandrel may be readily made to be suitable for the sinking of a smooth tube or a conical tube, or evenva tube having a non-circular cross section. Moreover, the aforesaid embodiment uses rubber pipes to cause a resilient return movement A of thev mandrel towards the contracted position, it being understood that the structural form thereof may be modified when use is made of other return means, f or instance springs connecting the sectors to the central member.

The mandrel includes several independent longitudinal sectors 1, for instance three in number, the curvature of the sectors substantially corresponding to that of the tube 2 to be sunk. Each sector has at its upper end a ange 3 through which it is connected to a flange 4 of a head 5 by means of bolts 6 which should not be tightened, since they are merely intended to serve as a means for suspending the mandrel on the head. Since the sectors 1 should be capable of performing a certain radial motion, the bolt-holes in the ilanges 3 are oval. In order to secure the radial guidance of the sectors there may be provided at the bottom of the head 5 a radial rib 7 adaptedto be engaged in a corresponding groove 8 in each llange 3. l

The percussion head is conveniently made in two sections, namely, the section 5, which is coupled to the sectors of the mandrel and a section 9, which forms a percussion block, the latter supporting an anvil member 10, o-f wood or the like, adapted to receive the blows of a hammer. The block 9 is guided vertically by guides 11 of the ramA and carries the section 5 by means of a link 12 arranged in the centre and providing for a certain oscillatory and gyratory movement of the mandrel. A safety cable 13, passing through holes in brackets 14, 15 provided on the block 9 and the sectors 1 respectively, will afford sustentation for the mandrel should the link 12 or the bolts 6 break.

Each sector 1 is formedwith two longitudinal inner projections 16, 17, the latter of which terminates in a hook-shaped web 18 at right angles to the said projections and comes short of the projection 16 which acts as a radial guide.

A central member 19 extends longitudinally between the sectors 1 and, in respect of each of them, the said member has a longitudinal projection 20 which is parallel to the projection 16 for cooperating as a radial guide means therewith and terminates in a web 21 which is parallel to the web 18 and extends into the space defined by the projections 16, 17, which space is thus divided into two compartments 22, 23.

The lower end of the central member 19 is secured, such as by welding, to an enlarged base 24 to which each sector 1 is coupled so as to be guided radially, by means of a pin 25 forming a radial guide member and engaging a bore forming a radial guide in the base 24. Where the sectors are in contact with the peripheral flange 26 of the base 24 they are strengthened and widened, for instance by means of strengthening members 27 which are welded to the lower end of the sectors.

A deformable pipe 28, for example of rubber, is arranged in each compartment 23 and is in communication with a source of compressed air or another fluid. In each compartment 22 there is arranged a resilient pipe 29, of rubber for instance, which has been simply cut ol at its upper end. The pipe 29 is so designed that upon being deformed it will develop a substantial force to assume again its circular shape as a result ,of its own elasticity.

yIn order to prevent the corrugated tube 2 from becoming distorted during the sinking operation, projections or helical ribs 30 maybe distributed `over the outer face of the sectors so :as to engage at least some of the corrugations of the tube.

To insert the ymandrel into Lthe tube or to puil it out therefrom, the compressed air is allowed to escape from the pipes 28, so that the proper elasticity of the pipes 29 causes the sectors 1 to return towards the central member 19 (Fig. 5). When the contracted mandrel has been inserted into Va tube 2 intended to be sunk, yall that need be done is to Ysupply compressed air tothe pipes 28, whereby to cause the mandrel vto expand (Fig. 4) and to press the sectors 1 against the tube 2 while applying a force which is related to -the strength of the latter and which may be readily-adjusted by-adjusting the pressure supplied to thespipes 28.

yIt will be found that the sectors and the central member land all of their projections as well extend over the entire height between the headS and the base 24 so that the whole of their cross section acts effectively in transmitting the drivingy stresses, without such parts having any tendency to get displaced with respect to each other under the action of inertia forces.

AThe full achievement of the aforesaid -result has been possible in `the first place due to the fact Ithat the pipes 28 and 29 termin-ate at their bottom in a narrowed portion 31, the reduced dimensions of Which have been .selected so as not to interfere with the con-traction of the mandrel so that there is no need for recessing the lower portion of the webs of the sectors yand of the central member, which recessingwould render them ineffective for the transmission of stresses and, in the second place, due to the fact that the outer pipes are in communication with a source of fluid by means of a connection extending through a window 32 formed in each sector -adjacent the upper end thereof, and also to the fact that the upper ends of the inner pipes 29 need not be provided with pipe connections, so that the recessing of vthe upper ends of the webs of the sectors and of the central member is avoided. Theoretically the pipes 29 could be cutoff lat their lower ends as well; however, `as will appear from fthefurther course of this disclosure, the construction illustrated is made to suit practical requirements aiming at placing the pipes in position more readily.

F1gs. 2 land3 sh-ow a side connection for the'pipes 28, yon lan enlarged scale. It comprises a metal body 33 secured 1n the end of the pipe 28 and provided with a laterally arranged'pipe connection 34, to which is attached the pipe 35 leading `to the source of oper-ating `fluid, and with an enlarged cup-shaped head 36 encloslng a buffer `pad 37, o-f rubber for instance, which engages an lnnerprojection'38 of the sector 1. The pad yabsorbs the inertia forces 'to which the pipe 28 .may be subjected during striking. The window 32 is wide enough lto -afford projection therethrough of the pipe connection shown in Figs. 2 and 3 when the mandrel is being contracted. The loss of strength in the sector 1 as ya result' i of` providing the window may be made up for by the provision of a strengthening frame 39 on the -outer surface of the sector. Thelateral extension of the pipes 28 through the sectors `'has the further ladvantage that the connections are visible and may be easily repaired, without the need of removing any components of the mandrel.

The pipes 28 and 29 are placed in position in the course :of assembling 'the mandrel, by pulling them through the cavities 22 and 23, respectively, which may vbe effected through -the agency of pulling means attached to threaded pins 40, 41 inserted into the sealed end of the pipes. Holes or apertures 42,143 `are provided in the 7d base 24 in order to enable the pulling means to move `through and, when the structure has been assembled, such "holes are stoppered with wooden blocks 42 and 43 or with readily removable fusing Imetal plugs.

It is to be understood that even in the most distended condition of the inner pipes 29, it is 'to say when the mandrel is completely contracted, such pipes should still be in some state of elastical bias as a result of being flattened or partially compressed. It follows that the insertion of such pipes which Will obviously be performed subsequently :to placing the -outer pipes 28v in position, may cause a certain amount of difficulty, which will also appear each time the inner pipes will have to be pulled out when the structure has to be taken to pieces or in view of a possible replacement. This will mainly be the case if the inner tubes 29 are not -able to cause the full contraction of the mandrel (-Fig. 5) by their own elasticity alone. All that need vbe done in this instance is to produce a vacuum in the pipes 28 by putting theminto com municati-on with a source of vacuum, e. g. by means .of a two-way cock 48, so as to reduce the pressure exerted upon the pipes 29 to a minimum. fSuch use of vacuum in 'the outer tubes may be made during operation if desired, in order to speed up and to magnify the contracting movement of the sectors with Ithe View of introducing the mandrel into the tube or withdrawing it therefrom, though the partial contraction caused Iby the proper elasticity of the inner pipes will'be sufficient, as a rule, Ito enable such -steps to beperiiormed.

`In order to increase the el-astical effect of the inner tubes, use may be made, if desired, of inner tubes 29 having `also their upper ends sealed and reduced.

In order that the mandrel may be used for sinking by means of a compressed plug of unset concrete or like compressible material, formed'at the lower end of 'the mandrel, provision is made of a small length of tube 44 welded to thebase 24 and adapted to contain the said concrete `and to prevent the latter vfrom interfering with lthe movement of the sect-ors. The upper end of the length of tube irl-ay lbe-sealed vby ia solid walkin which case ithe latter will -be provided with holes in register with the holes r42, 43 of the base 24, as shown in Fig. l.

In order that a mandrel as aforesaidfmay-be used-without resorting to the use of a concrete plug,a solid, removable foot 45 forming a driving point may beengaged in the tube 44 Vand held in position lby a pin 46, such 'foot having la goodbearing upon `a closure plate (not shown) of the base of tube 2. It will be understood that the mandrel may Ialso be used for sinkinga tube which is not provided with the aforesaid closure plate, both when a concrete plug is formed inthe tube 44 and when vthe mandrel isused with the foot 45.

Itis to be noted that the central member r19, 20, `21 may have provided on its top a steel plate or distributor 47 weldedftojthe various components of the said central member and, vfor instance, -tted `into a corresponding recess in the 'baseof'thehead 5, the said. plate serving as a strengtheningmernberand providing for a perfect distribution of the striking forces.

yIt willbe understood thatthe inventionisnot limited to the `construction described Vand illustrated, which may undergo various `changes without departing from ,thc spirit of Ithe invention.

I claim:

l. An expansible mandrel responsiveto driving means for sinking tubes into the ground, comprising ,an inner core structure includinga longitudinally Vextending central member having its upperendy adapted to be subjected to a driving force rapplied by saiddriving-means andan enlarged base including an upper'face and4 mechanically cured 'to said centraljmember for receiving the driving forces transmitted by, the central member, individual longitudinal sectors arranged around said innerI core structure and having their upper ends adapted `to bersubjectedto the driving force from said driving means and theirlower ends arranged to rest on the upper face of said enlarged base in operative driving position, first radial guide means on said inner core structure, second radial guide means provided on each of the sectors and each cooperating with the first guide means for radially guiding the sectors with respect to the inner core structure while prohibiting relative axial movement of the sectors with respect to the latter, elastic means between each of the sectors and the central member and tending to move the sectors towards the central member in order to contract the mandrel, and fluid pressure means between each of the sectors and the central member in order to cause the mandrel to expand against the action of the elastic means with uid pressure applied in the pressure means.

2. An expansible mandrel according to claim 1, in which each sector includes at least one inner longitudinal projection and the central member includes at least one outer projection for cooperating with said inner projection and radially overlapping the latter and peripherally spaced therefrom, said projections having their upper ends adapted to be subjected to the driving force and their lower ends in contact with the said enlarged base, the cooperating inner and outer projections including respective webs, the web of each inner projection overlapping the web on the cooperating outer projection and being radially spaced therefrom, the cooperating inner projections and outer projections thereby forming a series of outer chambers and a series of inner chambers being each radially aligned with an outer chamber, each inner chamber being located between two cooperating Webs and each outer chamber being located outwards of the web of an outer projection of the central member, between the last mentioned web and a member integral with a longitudinal sector, said fluid pressure means being constituted by deformable liuid tight pipes arranged in the outer chambers, said elastic means being arranged in the inner chambers.

3. An expansible mandrel according to claim l, in which said pressure means are constituted by longitudinally extending deformable huid-tight pipes having their lower ends sealed and reduced, the upper end of each of said Huid-tight pipes being provided with connecting means for connection to a source of uid and projecting laterally through a window provided in the corresponding sector, said connecting means terminating in a buffer pad, and an inner projection being provided on said corresponding sector above said window to form an abutment for said buffer pad.

4. An expansible mandrel according to claim l, in which the pressure means are constituted by deformable fluid-tight pipes, the lower ends of said deformable fluidtight pipes being sealed and reduced, the upper ends of said deformable fluid-tight pipes being provided with connecting means for connection to a source of uid.

5. An expansible mandrel according to claim 1, in

which the enlarged base of the central member is provided with a small length of tube which is integral therewith and extends downwardly and a driving point arranged in said length of tube and extending at least as far as the lower end thereof.

6. An expansible mandrel according to claim l, in which each sector is connected to the central member by means of a radial guide member which is integral with the sector and which is guided in a corresponding bore provided in the said base at right angles to the axis thereof.

7. An expansible mandrel according to claim l, in which each secto-r has a thickened lower end in engagement with a peripheral ange forming the lower part of the enlarged base of the central member.

8. An expansible mandrel according to claim 2, including a horizontal distributor plate secured to the upper end of the central member and the longitudinal projections thereof and in sliding contact with the upper end of the projections of the sectors, a percussion head having its lower face in contact with the upper ends of the sectors and said distributor plate, said percussion head being connected to the sectors by connections permitting limited radial movement of the sectors.

9. An expansible mandrel according to claim 2, in which said elastic means are constituted by deformable pipes having a predetermined elasticity.

l0. An expansible mandrel according to claim 2, in which the said elastic means are constituted by rubber pipes.

1l. An expansible mandrel according to claim 4, in which said connecting means include a multiway cock for controllably establishing communication with a source of uid under pressure and with a source of vacuum.

12. An expansible mandrel according to claim 9, in which apertures are pro-vided in the enlarged base of the central member in registration with the elastic pipes and with the deformable fluid-tight pipes respectively, said apertures being scalable by removable plugs.

13. An expansible mandrel according to claim 9, in which the elastic pipes are open at least at one of their ends.

14. An expansible mandrel according to claim 9, in which the elastic pipes are sealed and reduced at least at one of the ends thereof.

References Cited in the le of this patent UNlTED STATES PATENTS 1,491,832 Upson Apr. 29, 1924 1,912,089 Moe May 30, 1933 2,437,043 Riemenschneider et al. Mar. 2, 1948 2,625,015 Cobi Ian. 13, 1953 2,684,577 Smith July 27, 1954 2,708,994 Kraft May 24, 1955 

